running

New research suggests the biggest animals run out of fuel for their fast-twitch muscles before they reach the maximum speed their bodies could achieve. Animals like cheetahs are born to run fast.

Six years ago, China held 22 marathons; this year, more than 400 are scheduled. But it's long-distance running with Chinese characteristics, and some twists including cigarettes and fruity soap.

Scientists at the University of California, Berkeley have figured out why shoelaces seem to come untied at the worst moments, like when you're running.

To curb diabetes, Mexico is trying to get people to cut down on soda, eat more healthful foods and exercise. But changing people's habits is easier said than done.